1. Field of the Invention
The instant invention relates to catheters and more particularly to a urinary Foley catheter having an outer membrane which reduces irritation to the urethra caused by the catheter and allows for medicament, particularly antimicrobial or anti-bacterial medicament, or other liquids to be placed in the urethra through the membrane while the catheter is in place in the patient's urethra.
2. Description of Related Art
Urethral catheters are known that are placed within a patient's lower urinary tract. One type of urethral catheter is a retention catheter. Retention catheters connect the patient's bladder to the meatus of the patient to continuously remove urine from the patient's bladder. One type of urinary retention catheter is a Foley catheter.
As shown in FIG. 1, a typical Foley catheter 1 consists of an elongated tube 12 having a proximal end 14 and a distal end 16. A main lumen 18 extends from the proximal end 14 to the distal end 16. The catheter 1 is placed through the patient's urethra so that the distal end 16 extends into the patient's bladder and the proximal end remains outside the patient's body. The distal end 16 has an inlet opening 20 to allow urine to pass into the inlet opening 20 and through main lumen 18 of the elongated tube 12. The main lumen 18 extends to a connecting funnel 22 at the proximal end 14 which allows the urine to pass into a collection bag.
Foley catheters have a means for retaining them in position within the patient's bladder and urethra in the form of an inflatable balloon 24 located at the distal end 16 of the elongated tube 12 proximal to the inlet opening 20. An inflation lumen 26 connects the balloon 24 to the proximal end 14 of the catheter 10 so that a liquid may be passed under pressure through the inflation lumen 26, through inflation outlet 28 into balloon 24 to expand the balloon 24. A valve 30, such as is well known in the art, is also provided to maintain the liquid under pressure so that the balloon 24 remains inflated.
In operation, the distal end 16 of the catheter 1 is pushed through a patient's urethra into the patient's bladder a sufficient distance so that the balloon 24 is also within the bladder. The balloon 24 is then expanded within the patient's bladder to secure the catheter against movement in the proximal direction through the urethra. In a urethral catheter including such a balloon 24, the cross-section of the elongated tube 12 includes a main lumen 18 through which urine passes and an inflation lumen 26, typically smaller than the main lumen 18, through which the liquid passes from the proximal end 14 of the catheter to the balloon 24 for inflating the balloon 24.
In another embodiment of the catheter, an additional medicament lumen 32 is provided which extends from the proximal end 14 of the catheter to an outlet 34 located distal to the balloon 24. When this catheter is placed within the patient's urethra and retained in position in the patient's bladder, this outlet 34 is within the patient's bladder. Typically, medicaments are passed through this lumen 32 into the patient's bladder.
Recent studies have shown that hospital acquired or "nosocomial" urinary tract infections (UTI) affect about 900,000 Americans annually. J. R. Johnson, P. L. Roberts, R. J. Olsen, K. A. Moyer, and W. E. Stann, Prevention of Catheter Associated Urinary Tract Infection with a Oxide-Coated Urinary Catheter Clinical and Microbiologic Correlates, 162 Journal of Infectious Diseases, 1145-1150 (1990). Many of these UTIs are acquired in hospitals with the result that UTIs account for about 40% of all hospital acquired infections. Id. Of the UTIs acquired in hospitals, about 80% are catheter associated. Id. These hospital related UTIs prolong hospital stay by an average of 2.4 to 4.5 days and increase the hospital cost by $558.00 per episode. Id. If the percent of catheter associated UTIs could be reduced to 0, the annual saving in hospital cost alone could be reduced by $401,760,000.00.
An additional problem with UTIs associated with catheter use is that 1-3% of these patients develop bacteremia. Bacteremia is a potentially mortal disease. Therefore, it is clearly desirable to reduce the possibility of developing bacteremia.
A source of the catheter related UTIs is suspected to be bacteria progressing from the patient's meatus through the peri-urethral space into the bladder. One method in the prior art for attempting to prevent bacterial caused UTIs is disclosed in U.S. Pat. No. 4,773,901 to Norton. In the Norton patent, the urinary catheter is coated with silver oxide to kill bacteria which may find its way down the patient's periurethral space. However, for many applications, the device of the Norton patent has not proved to be totally effective. As a result, in these applications, a substantial probability of acquiring a UTI still exists when using the Norton device.
It is believed that the number of UTIs resulting from catheter use could be significantly reduced if antimicrobial material could be placed along the urethra to prevent the colonization and passage of the bacteria as desired while the catheter is in place within the patient's urethra.